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[BUG] bool(DashTable) is always False about dash HOT 4 OPEN

JakkuSakura commented on July 17, 2024

[BUG] bool(DashTable) is always False

from dash.

Comments (4)

T4rk1n commented on July 17, 2024 1

The condition for components is based on it's __len__ property,

dash/dash/development/base_component.py

Lines 369 to 389 in 1cb7455

 def __len__(self): 

 """Return the number of items in the tree.""" 

 # TODO - Should we return the number of items that have IDs 

 # or just the number of items? 

 # The number of items is more intuitive but returning the number 

 # of IDs matches __iter__ better. 

 length = 0 

 if getattr(self, "children", None) is None: 

 length = 0 

 elif isinstance(self.children, Component): 

 length = 1 

 length += len(self.children) 

 elif isinstance(self.children, (tuple, MutableSequence)): 

 for c in self.children: 

 length += 1 

 if isinstance(c, Component): 

 length += len(c) 

 else: 

 # string or number 

 length = 1 

 return length

It only looks for the children prop to determine this and the DataTable doesn't have a children prop. You can workaround this by looking at bool(tb.data) instead.

from dash.

alexcjohnson commented on July 17, 2024

Would it be reasonable to add an explicit __bool__ for components that’s always True? That could be useful for cases where a variable might be a component or might be None.

from dash.

JakkuSakura commented on July 17, 2024

Yeah it would be helpful

from dash.

JakkuSakura commented on July 17, 2024

bool(tb.data) it's not a direct replacement of bool(tb), as it might be None and raise None value exception

from dash.

[BUG] bool(DashTable) is always False about dash HOT 4 OPEN

Comments (4)

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	def __len__(self):
	"""Return the number of items in the tree."""
	# TODO - Should we return the number of items that have IDs
	# or just the number of items?
	# The number of items is more intuitive but returning the number
	# of IDs matches __iter__ better.
	length = 0
	if getattr(self, "children", None) is None:
	length = 0
	elif isinstance(self.children, Component):
	length = 1
	length += len(self.children)
	elif isinstance(self.children, (tuple, MutableSequence)):
	for c in self.children:
	length += 1
	if isinstance(c, Component):
	length += len(c)
	else:
	# string or number
	length = 1
	return length